1. Field of the Invention
The present invention relates to a fastening element for hard constructional components such as concrete, masonry and the like and including a cylindrical base body extending along a longitudinal axis and having a first end and a second end opposite from the first end, a self-tapping thread provided, at least regionwise, on the outer surface of the base body and having a runout spaced from the first end to provide a thread-free section extending from the first end and in the direction of the second end, inwardly located engagement means for the setting bit, and an opening that is open toward the second end of the base body and, adjoins the engagement means in a direction toward the second end, and load application means.
2. Description of the Prior Art
Fastening elements of the type described above are used for attachment of objects to the hard constructional components such as concrete, masonry, and the like. A fastening element is screwed in a preliminary formed borehole with a suitable setting bit, with the self-tapping thread forming a complementary thread in the constructional component or in the borehole wall. The fastening elements is anchored in the constructional component by the undercut formed by the complementary thread. The load application means, which is provided in the receptacle, is formed, e.g., as an inner thread into which an attachment element, such as e.g., a threaded rod or a screw is screwed in to form an attachment. Instead of the inner thread, a bayonet joint can be used.
International Application WO 01/88387 A1 disclose a fastening element described above. The fastening element has a cylindrical base body extending along a longitudinal axis and having a first end facing in a setting direction and an opposite second end. On the outer surface of the base body, there is provided a self-tapping thread with three cutter helically circumferentially circumscribing the base body at an end region at the first end and which form a three-point support. The base body has inwardly located engagement means for a setting bit, and a receptacle opening that opens toward the second end and adjoins the engagement means in a direction of the first end, and is provided with load application means formed as an inner thread.
The drawback of the above-described fastening element consists in that as a result of the arrangement of the engagement means at the second end of the base body, the fastening element has a tendency to tilt during a setting process. This makes the setting process more difficult and widens the borehole mouth in an undesirable manner.
European Publication EP 1 536 149 A2 discloses a fastening element of a type described above. The known fastening element has a cylindrical base body having a first, facing in the setting direction, end with a bottom section and a second and remote from the first end. On the outer surface of the base body, a self-tapping thread is provided. The base body has inwardly located, engagement means for the setting bit and a receptacle opening to the second end and adjoining, in the direction toward the second end, the engagement means. The receptacle is provided with an inner thread that forms load application means. In the end region of the first end, the engagement means is arranged at the same axial height of the base body as the thread runout of the self-tapping screw.
The drawback of the known fastening element consists in that formation of the engagement means at the bottom of the receptacle is connected with increased manufacturing costs, being costs-intensive. Further, with such fastening element, manufacturing possibilities are limited. Actually, at a mass production, for which such fastening elements are suited, an economical manufacturing is an important competitive advantage.
Accordingly, an object of the present invention is to provide a fastening element for hard constructional components with which the tendency to tilting is eliminated to a most possible extent.
Another object of the present invention is to provide a fastening element for hard constructional components and which can be economically produced.